iirfilter.h File Reference

IIR filter interface. More...

#include "avcodec.h"

Go to the source code of this file.

Enumerations
enum	IIRFilterType {   FF_FILTER_TYPE_BESSEL, FF_FILTER_TYPE_BIQUAD, FF_FILTER_TYPE_BUTTERWORTH, FF_FILTER_TYPE_CHEBYSHEV,   FF_FILTER_TYPE_ELLIPTIC }
enum	IIRFilterMode { FF_FILTER_MODE_LOWPASS, FF_FILTER_MODE_HIGHPASS, FF_FILTER_MODE_BANDPASS, FF_FILTER_MODE_BANDSTOP }

Functions
struct FFIIRFilterCoeffs *	ff_iir_filter_init_coeffs (void *avc, enum IIRFilterType filt_type, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband, float ripple)
	Initialize filter coefficients.
struct FFIIRFilterState *	ff_iir_filter_init_state (int order)
	Create new filter state.
void	ff_iir_filter_free_coeffs (struct FFIIRFilterCoeffs *coeffs)
	Free filter coefficients.
void	ff_iir_filter_free_state (struct FFIIRFilterState *state)
	Free filter state.
void	ff_iir_filter (const struct FFIIRFilterCoeffs *coeffs, struct FFIIRFilterState *state, int size, const int16_t *src, int sstep, int16_t *dst, int dstep)
	Perform IIR filtering on signed 16-bit input samples.
void	ff_iir_filter_flt (const struct FFIIRFilterCoeffs *coeffs, struct FFIIRFilterState *state, int size, const float *src, int sstep, float *dst, int dstep)
	Perform IIR filtering on floating-point input samples.

Detailed Description

IIR filter interface.

Definition in file iirfilter.h.

Enumeration Type Documentation

enum IIRFilterType

Enumerator:

FF_FILTER_TYPE_BESSEL
FF_FILTER_TYPE_BIQUAD
FF_FILTER_TYPE_BUTTERWORTH
FF_FILTER_TYPE_CHEBYSHEV
FF_FILTER_TYPE_ELLIPTIC

Definition at line 35 of file iirfilter.h.

enum IIRFilterMode

Enumerator:

FF_FILTER_MODE_LOWPASS
FF_FILTER_MODE_HIGHPASS
FF_FILTER_MODE_BANDPASS
FF_FILTER_MODE_BANDSTOP

Definition at line 43 of file iirfilter.h.

Function Documentation

struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs ( void *  avc, enum IIRFilterType  filt_type, enum IIRFilterMode  filt_mode, int  order, float  cutoff_ratio, float  stopband, float  ripple  )

read

Initialize filter coefficients.

Parameters

avc	a pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct
filt_type	filter type (e.g. Butterworth)
filt_mode	filter mode (e.g. lowpass)
order	filter order
cutoff_ratio	cutoff to input frequency ratio
stopband	stopband to input frequency ratio (used by bandpass and bandstop filter modes)
ripple	ripple factor (used only in Chebyshev filters)

Returns

pointer to filter coefficients structure or NULL if filter cannot be created

Definition at line 159 of file iirfilter.c.

Referenced by ff_psy_preprocess_init().

struct FFIIRFilterState* ff_iir_filter_init_state ( int  order )

read

Create new filter state.

Parameters

order

filter order

Returns

pointer to new filter state or NULL if state creation fails

Definition at line 201 of file iirfilter.c.

Referenced by ff_psy_preprocess_init().

void ff_iir_filter_free_coeffs

(

struct FFIIRFilterCoeffs *

coeffs

)

Free filter coefficients.

Parameters

coeffs

pointer allocated with ff_iir_filter_init_coeffs()

Definition at line 305 of file iirfilter.c.

Referenced by ff_iir_filter_init_coeffs(), and ff_psy_preprocess_end().

void ff_iir_filter_free_state

(

struct FFIIRFilterState *

state

)

Free filter state.

Parameters

state

pointer allocated with ff_iir_filter_init_state()

Definition at line 300 of file iirfilter.c.

Referenced by ff_psy_preprocess_end().

void ff_iir_filter	(	const struct FFIIRFilterCoeffs *	coeffs,
		struct FFIIRFilterState *	state,
		int	size,
		const int16_t *	src,
		int	sstep,
		int16_t *	dst,
		int	dstep
	)

Perform IIR filtering on signed 16-bit input samples.

Parameters

coeffs	pointer to filter coefficients
state	pointer to filter state
size	input length
src	source samples
sstep	source stride
dst	filtered samples (destination may be the same as input)
dstep	destination stride

Definition at line 274 of file iirfilter.c.

void ff_iir_filter_flt	(	const struct FFIIRFilterCoeffs *	coeffs,
		struct FFIIRFilterState *	state,
		int	size,
		const float *	src,
		int	sstep,
		float *	dst,
		int	dstep
	)

Perform IIR filtering on floating-point input samples.

Parameters

coeffs	pointer to filter coefficients
state	pointer to filter state
size	input length
src	source samples
sstep	source stride
dst	filtered samples (destination may be the same as input)
dstep	destination stride

Definition at line 287 of file iirfilter.c.

Referenced by ff_psy_preprocess().